The original outdoor game with excessive attendance of 10s of 1000s of fans was not even an National Hockey League event.
And no, it was not even the Michigan-Michigan State Cold War showdown back in 2001.
No, the original outdoor game truly had a Cold War setting - Moscow, 1957.
The final game of World Hockey Championships was held at Moscow's Lenin Stadium. A sold out crowd of as many as 55,000 people watched Sweden tie the Russians 3-3, allowing the Swedes to sneak out of Russia with their 2nd world championship ever.
A couple of interesting stories about that game:
1) A big reason Sweden was in gold medal contention was the fact that Canada and the United States boycotted the tournament due to the Soviet occupation of Hungary.
2) Upon celebrating their gold medal victory, Swedish defenseman Lasse Bjorn, the grandfather of current San Jose Shark Douglas Murray, was asked to sing the Swedish national anthem before everyone. Under pressure, Bjorn blanked on the words so he began singing the popular Swedish drinking song "Heland Ger," Let's Drink It All!